I'm trying to answer three main questions:
- Does a three-axis biome chart make sense for my world?
- How productive/life-rich should a biome be given a specific level of solar flux (holding temperature and precipitation steady)
- Can we quantify or qualify that level of productivity/life-richness in the biome? (This could be comparative: "as productive as Earth's equatorial rainforest, as productive as the African Savannah, etc.)
As part of my world-building I've developed an alien world. It's mostly earth-like (oceans, continents, similar atmosphere, roughly earth-like average temperature) but varies in a few big ways. Something I'm struggling with is determining how "life rich" each of its biomes should be, and how to delineate those biomes.
By "life rich" I mean something like the quantity of life you'd see within the biome. The productivity. The energy throughput. For example, on Earth a tropical rain forest is a very "rich" biome, while the tundra is not. A temperate forest in summer is a moderately rich biome, while in winter it is not.
You may be familiar with biome graphs like this one:
They are work well for Earth given only two variables: precipitation and temperature. This is a generalization of course, since many factors determine the exact biome, including elevation and seasonal distribution of precipitation. However it's a good rule of thumb...for Earth.
As useful as charts like this one are for world-builders, they run into big hiccups when dealing with my alien world. The principal problem I see here is that—unlike Earth–my world exhibits variable combinations that don't exist on Earth.
I think biome charts like the one work on Earth because temperature correlates closely with latitude, and therefore with average solar insolation (i.e. energy from the sun). My world however doesn't work this way. On my world the following variables can be considered semi-independent:
- Average Solar Insolation (Flux)
Unlike on Earth, you can have a biome that is both warm and wet (like a tropical forest) BUT it has average levels of solar flux similar to Norway. You also have biomes that are hot, wet (like tropical forests) but get 2x the average solar flux of a spot on Earth's equator.
There are also two other big variables on my world that will play a roll:
- Received Sunlight Wavelength: Amount of visible vs infrared varies based on longitude and time of year (thanks binary star!)
- Ratio of daylight/night-time over one full day-length: Varies by longitude (think orbital resonance, like mercury)
My idea is instead to create a three-axis chart as my base based on temperature, solar insolation, and precipitation. I'll then factor in the last two variables later on to go into more detail.
Does that sound like a viable approach?
Key to this is figuring out how "productive" and "life rich" a biome should be given its average amount of flux. My biomes vary widely, with average flux varying by BOTH longitude AND latitude (Earth's only varies by latitude). An example is the equator of my world. The flux at 0N and 0E is about 770w/m2 in the winter and 890w/m2 in the summer. At 0N and 180E it's about 220w/m2 in the winter and 335w/m2 in the summer.
Note: Average solar flux for Earth at Equinox is:
On my world you have locations with variables combinations like this:
Equatorial Spot #1:
- Warm (Summer), Cool (Winter)
- Moist to Dry (seasonal)
- Low Average Sunlight Flux (280 w/m2 per hour)
- Summers: More flux (and bigger % from visible wavelengths)
- Winter: Less flux (and bigger % from infrared wavelengths)
- Long nights, short days
Equatorial Spot #2:
- Very Hot (year-round)
- Very Wet
- Very High Average Sunlight Flux (800w/m2 per hour)
- Summers & Winters: Low seasonal flux variation by %
- Long days, short nights
Mid-Latitude Spot #3:
- Hot (Summer), Cool (Winter)
- High Average Sunlight Flux (400 w/m2 per hour)
- Seasonal Flux Change: Moderate (in-between #1 and #2)
- Equally split day/night length
Note: A full seasonal cycle (spring, summer, autumn, winter) is nearly an Earth-decade long.